Vehicle heater with control device

ABSTRACT

An engine-independent vehicle heating appliance has a combustion air fan, a fuel dosing pump and a heat exchanger that surrounds the combustion chamber, as well as a controller that controls the operation of the vehicle heating appliance. In compact designs, special measures are required to protect the electronic components of the controller from overheating. In order to carry off heat in an effective manner, the controller has a heat conducting plate upon which the electronic power components (18) are mounted, their connections being electrically connected to the wiring on the board (16). Loss heat that results from the operation of the components (18) is carried away by the material of the heat conducting plate (8a, 8b) to the fan housing (6). Since the latter is always cool a sufficient cooling of the components (18) is ensured.

FIELD OF THE INVENTION

The present invention pertains to a vehicle heater with a burner, towhich combustion air is fed by a combustion air blower equipped with ablower housing and to which fuel is fed by a fuel feed pump in order togenerate a flame in a combustion chamber surrounded by a heat exchanger,and with a control device having electronic components arranged on acircuit board for controlling the operation of the vehicle heater.

BACKGROUND OF THE INVENTION

Such engine-independent vehicle heaters are used as auxiliary heaters inmotor vehicles, but also in motor yachts, small airplanes, recreationalvehicles, construction equipment, and the like.

The currently usual embodiments of such vehicle heaters use as the heatcarrier water or water with antifreeze which is circulated by means of acirculating pump through a heating circuit containing a heat exchanger.A temperature sensor at the heat exchanger detects the temperature ofthe heat carrier, and the operation of the vehicle heater is controlledas a function of this temperature and other parameters, e.g., thedesired temperature set. The control is assumed by the electroniccontrol device, which receives condition signals from various parts ofthe vehicle heater, including the above-mentioned temperature sensor,and sends control and switching signals to defined parts of the heater,e.g., to the combustion air blower motor, the fuel feed pump, thecirculating pump, the ignition unit, etc.

In many of the currently common vehicle heaters, the control device islocated in the installed state at a point remote from the combustionchamber, because the electronic components of the control device aresusceptible to the temperature and must be protected from heating by,e.g., the heat radiated by the combustion chamber and by the heatexchanger. Arranging the control device at a point remote from the otherparts of the device can be achieved with relative ease, because onlyelectric connections are necessary between the control device and theother parts of the heater.

However, the installation of these heaters, in which at least thecontrol device, but optionally also the fuel feed pump and other partsare arranged at a point remote from the heat exchanger, i.e., the mainbody of the device, is labor-intensive. It would be considerably simplerto install the vehicle heater if it contained all components and itwould thus be able to be installed as a compact assembly unit withoutmuch trouble.

However, it is not easy to design the vehicle heater as a compactassembly unit, which accommodates in itself all essential components ofthe device. One reason that argues against the compact design of thevehicle heater is, e.g., the above-mentioned requirement that theelectronic components of the control device must not be excessivelyheated. However, if the control device is arranged at a short distancefrom the heat exchanger, sufficient cooling of the electronic componentsof the control possibly may not be guaranteed.

SUMMARY AND OBJECTS OF THE INVENTION

The object of the present invention is to provide a vehicle heater ofthe type described in the introduction in which it is always ensuredthat the electronic components of the control device are not excessivelyheated even in the case of compact design of the vehicle heater.

This object is accomplished according to the present invention with avehicle heater of the above-described type by the control device beingfastened to the blower housing and by at least one heat-conductingconnection being formed between the blower housing and the controldevice.

Even though there is a certain proximity to the electric drive motor ofthe blower due to the close proximity of the control device to thecombustion air blower, so that heat may reach the components of thecontrol device from the drive motor, this effect can be practicallyignored, because it is guaranteed due to the heat-conducting connectionbetween the blower housing and the control device that the heat due toenergy loss, which is generated by the electronic components, especiallythe electronic power components, can be adequately diverted into theblower housing. The housing of the combustion air blower is inherentlyone of the coolest points of the entire vehicle heater, because arelatively cool air flow flows through the blower during the operationof the heater. If the control device contains, e.g., driving transistorsfor driving the fuel feed pump or the like, the transistors generate aconsiderable power loss. This power loss, manifested as heat, is readilyremoved via the combustion air blower due to the arrangement of thecontrol device according to the present invention.

In a special embodiment of the present invention, components of thecontrol device are arranged on a circuit board; the circuit board isconnected to a heat-conducting plate, and at least part of thecomponents of the control device are mounted on the heat-conductingplate arranged on the blower housing. As was said, these are mainlypower components which generate so much power loss in the form of heatduring operation that a special cooling is indispensable.

In a geometrically especially preferred embodiment, the heat-conductingplate is arranged at right angles to the circuit board and preferablyconnected to same in one piece. Due to this embodiment, the electronicpower components of the control device can be mounted flatly on theheat-conducting plate, and the terminals projecting from the componentin parallel to the heat-conducting plate can be led into the contactingholes of the circuit board provided for this purpose. Theheat-conducting plate is then arranged on the "underside" of the sidechannel blower of the combustion air blower facing the drive motor. Theblowers in the vehicle heaters being discussed here are usually sidechannel blowers, so that the above-described arrangement of theheat-conducting plate of the control device is recommended.

An especially important, but at the same time good utilization of thespace available is achieved by the heat-conducting plate having a baseplate arranged flatly on the blower housing and a projection made in onepiece therewith, and by one or more power components, whose electricterminals are connected to the board, being mounted on the projection.Consequently, the power components do not need to be arranged directlyon the base plate, which is flatly in contact with the combustion airblower housing; sufficient heat dissipation is achieved even in the caseof arrangement on the above-mentioned projection.

The space-saving arrangement according to the present invention isfurther improved by the fact that the control device is arranged on theblower housing such that it extends approximately in parallel to thelongitudinal axis of the blower motor. The motor is usually of acylindrical shape, whose diameter is smaller than the diameter of theside channel blower. If the outer circumference of the side channelblower is extended along the axis of rotation of the blower motor, aspace, which is used according to the present invention to accommodatethe components of the control device, is obtained in the circumferentialarea of the drive motor. An extremely compact design is achieved hereby,but sufficient cooling of the power components is still guaranteedbecause of the special arrangement of the heat-conducting plate of thecontrol device on the combustion air blower.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich a preferred embodiment of the invention is illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic, partially cutaway top view of a combustion airblower with part of a control device;

FIG. 2 is a perspective view of essential parts of the control devicewith circuit board, heat-conducting plate, a patch plug, and electronicpower components; and

FIG. 3 is a perspective view of the control device according to FIG. 2,but covered by the housing of the control device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The essential components of a vehicle heater were already mentionedabove and are not specifically shown in the drawings. However, theperson skilled in the art knows that how such vehicle heaters aredesigned, so that a detailed explanation of the general design of suchheaters is unnecessary.

FIG. 1 shows a top view of a combustion air blower 2 with an electricblower motor 4 and with a blower housing 6. The blower motor 4 has anapproximately cylindrical shape, and a drive shaft, which is not shownand at the top end of which the impeller of a side channel blower isarranged, extends concentrically therewith. The elements of the sidechannel blower are indicated by broken lines within the blower housing6.

If the circumferential wall of the blower housing 6 is meant to becontinued downward in FIG. 1, an annular space, which is used toaccommodate the control device of the vehicle heater here, is obtainedoutside the blower motor 4. The said space surrounding the blower motor4 may be closed by a cover 24.

FIG. 2 shows a perspective view of a control device 12 with a patch plug14, which is mounted, like the power components 18 and 20 as well asadditional components, not shown in the drawing, on a board 16. Theboard 16 is designed as a usual circuit board, whose horizontalprojection is adapted to the cross-sectional shape of the vehicleheater, which shape is of no interest here.

A heat-conducting plate 8, which is rigidly connected to the board 16and consists of a flat base plate 8a and a projection 8b joining it atright angles, extends at right angles to the plane of the board 16. Theheat-conducting plate 8 consists of heat-conducting aluminum.

Holes 10, which are used to fasten the entire control device shown inFIG. 2 on an underside 6a of the blower housing 6 by means of screws 9,are located at the edges of the base plate 8a. As can be seen in FIG. 1,the top side of the base plate 8a, which is visible at the top of FIG.2, is flatly in contact with the underside of the blower housing 6, sothat good heat transfer between these parts is possible. The blowerhousing 6 is always relatively cool during the entire operation of thevehicle heater, so that heat reaching the base plate 8a is rapidlytransferred to the blower housing 6.

FIG. 2 also shows that electronic power components 18 and 20 arearranged on the front side of the projection 8a, which is visible inFIG. 2, and on its rear side. The heat due to energy loss which isgenerated in the power components is readily conducted to the materialof the projection 8b due to the flat arrangement of the power components18 and 20 in order to reach the base plate 8a from there. The powercomponents 18, 20 are electrically connected with connection pins 22 tothe corresponding strip conductors on the circuit board 16. To simplifythe representation, these strip conductors are not shown in thedrawings.

FIG. 3 shows the control device according to FIG. 2 in a state in whichit is covered by a control device housing 30. A recess 28, into whichpart of the outer wall of the blower motor 4 is fitted, is recognized.

The cooling measures described above, namely, the mounting of the powercomponents 18 and 20 on the heat-conducting plate 8, which is fastenedto the underside 6a of the blower housing 6, guarantee sufficientcooling. An additional ventilation of the control device housing 30 maybe provided for safety, so that an air flow additionally flows throughthe interior of the housing 30.

The patch plug 14 is a socket part and it makes possible a rapidconnection of the control device to the individual components of thevehicle heater via a cable, at the end of which a patch plug fitting thepatch plug 14 is located.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

I claim:
 1. A vehicle heater, comprising:a burner; a combustion airblower for feeding combustion air to the burner, said combustion airblower including a blower housing; a fuel feed pump, said burnerincluding a combustion chamber surrounded by a heat exchanger, said fuelfeed pump for feeding fuel to said burner in order to generate a flamein said combustion chamber; a control device arranged on a circuit boardand containing electronic components for controlling the operation ofsaid burner; heat conduction means providing a heat conductingconnection between said blower housing and said control device, saidcontrol device being fastened at said heat conduction means to saidblower housing.
 2. A vehicle heater according to claim 1, wherein saidelectronic components of said control device are arranged on saidcircuit board, said heat conducting connection including a heatconducting plate, said circuit board being connected to said heatconducting plate with at least some of said electronic components beingmounted on said heat conducting plate.
 3. A vehicle heater according toclaim 2, wherein said heat conducting plate is arranged at a right anglewith respect to said circuit board.
 4. A vehicle heater according toclaim 3, wherein said circuit board is connected to said heat conductingplate in one piece.
 5. A vehicle heater according to claim 3, whereinsaid heat conducting plate is formed of a single piece.
 6. A vehicleheater according to claim 3, wherein said heat conducting plate includesa base plate arranged to lie flat on a flat blower housing surface andsaid heat conducting plate includes a projection formed integrally withsaid heat conducting plate, one or more of said electrical componentsbeing power components with electrical terminals connected to saidcircuit board, mounted on said projection.
 7. A vehicle heater accordingto claim 1, wherein said control device is arranged on said blowerhousing, said blower including a blower motor, said control deviceextending approximately in parallel to a longitudinal axis of saidblower motor.
 8. A vehicle heater according to claim 1, wherein:saidheat conduction means directly conveys heat from said electroniccomponents to said blower housing.
 9. A vehicle heater according toclaim 1, wherein:said heat conduction means directly contacts saidelectrical components and said blower housing.
 10. A vehicle heateraccording to claim 1, wherein:said heat conduction means includes a baseplate arranged to lie flat on a flat blower housing surface and saidheat conduction means includes a projection connected to said baseplate; one or more of said electrical components being power componentswith electrical terminals connected to said circuit board, mounted onsaid projection.
 11. A vehicle heater in accordance with claim 10,wherein:said base plate and said projection are formed integrally witheach other.